The class of polycarbonate polymers is broadly known in the art. An early review article by Schnell, Industrial and Engineering Chemistry, Vol. 51, No. 2, pp. 157-160 (1959), describes properties of the class of polycarbonates and methods known in the art at that time for the preparation of polycarbonate polymers including certain polycarbonate polymers which are now commercial. In general, the polycarbonate polymers are thermoplastics whose glass transition temperatures will depend upon the nature and symmetry of the groups incorporated into the polycarbonate chain other than the carbonyldioxy groups. Most polycarbonates are derived from a bisphenol and commercial polycarbonates are frequently derived from 2,2-di(4-hydroxyphenyl)propane, also known as bisphenol A or BPA. The polycarbonate polymers are conventionally produced by reaction of a bisphenol or an alkali metal salt thereof with phosgene or by ester exchange with a diaryl carbonate, particularly diphenyl carbonate.
These polymers are processed by conventional methods employed for thermoplastics such as injection molding or extrusion into films, sheets, fibers, tubing and shaped articles. The articles produced from polycarbonate polymers demonstrate good resistance to oxygen, heat and light as well as to common solvents.
The preparation of cyclic polycarbonates and their conversion to linear polycarbonates is known, for example, in U.S. Pat. Nos. 4,605,731, 4,644,053, 4,727,134 and 4,740,583. It would be of advantage to provide a novel class of cyclic polycarbonate oligomers containing multiple rings, which can be used to prepare linear polycarbonate polymer products.